The invention relates to a device for measuring a tire pressure of a tire arranged on a rim, having a tire valve arranged in a bore in the rim, and a tire pressure sensor unit arranged inside the tire and fastened on the tire valve, it being possible, according to the embodiment, to fasten the tire pressure sensor unit in various angular positions with reference to the tire valve.
Devices of this generic type are used in order to monitor the tire pressures in the tires of motor vehicles. This can be performed such that use is made of an automatic monitoring system that outputs warnings upon undershooting or overshooting of critical values. A device of the generic type is also used to indicate the tire pressures continuously in the interior of the vehicle.
The measured values of the tire pressure sensor unit are transmitted in a wireless fashion to a receiver that then makes available the signals that are to be evaluated and/or displayed. In order to render possible such wireless transmission, it is necessary to provide in the region of the tire pressure sensor unit a transmitting antenna that can also serve occasionally as a receiving antenna, for example for receiving trigger signals. Such an antenna is generally permanently connected, as part of the tire pressure sensor unit, to an electronic printed circuit board of the tire pressure sensor unit. This is advantageous in some regards, in particular concerning the reliable electric connection of the antenna to the printed circuit board. This applies, chiefly, when, as in the case of the device of the generic type, it is possible to adjust the angle of the tire pressure sensor unit. In this case, the electric connection of the antenna to the tire pressure sensor unit is not influenced by the respective angular position.
In another regard, however, disadvantages have to be noted, since a printed circuit board antenna requires installation space as an additional component of the tire pressure sensor unit, and increases the complexity of the unit.